The present invention relates to soft capsule making and more particularly to a tumbler-dryer used for making soft capsules.
Typical soft encapsulation machines for use in making pharmaceutical medicines form at least two flexible gelatin sheets or ribbons by cooling molten gelatin on separate drums. The sheets are lubricated and guided into communication with each other over co-acting dies. Simultaneously, a desired quantity of fill material is dispensed between the sheets in synch with cavities in the outer surfaces of the dies to produce soft capsules. The soft capsules are transported from the encapsulation machine to a drying machine to dry (in other words, remove moisture from) the soft capsules and make them into their final form. The soft capsules are typically transported from the encapsulation machine to the dryer by a conveyor that extends along the front of the encapsulation machine.
The drying machine typically includes a plurality of axially aligned drying drums or baskets. The baskets are arranged adjacent one another and allow capsules to flow from one basket into the next adjacent basket. Heated air is routed through the various baskets to dry the capsules therein. Furthermore, after passing through the drying baskets, the capsules may also need to be routed through a drying tunnel wherein further moisture is removed from the capsules to obtain the desired state of dryness or moisture content. This drying process can require a significant number of baskets to dry the capsules to a desired moisture content. The capsules get dryer in each subsequent drying basket they flow into. This results in a large dryer requiring a large foot print or area of a factory in which it is employed. Furthermore, the use of drying tunnels also undesirably increases the area or footprint of the overall drying equipment required to dry the capsules to a desired moisture content.
Space in the manufacturing facility, however, may be at a premium. Therefore, it would be advantageous to reduce the size and/or footprint of the drying machines. Furthermore, it would be even more advantageous if a larger capacity or throughput can be achieved in the same or smaller footprint.
Typically, all of the baskets of conventional machinery are driven at a same rotational speed by a single belt drive unit. The required rotational speed of the baskets, however, can vary based upon the moisture content in the capsules. Thus, as the capsules get dryer and pass from one drying basket to the next, the required rotational speed may change. Since all the baskets are driven at the same rate of speed by a single belt drive mechanism, however, all of the baskets must be rotated at the same speed which will correspond to the speed of the most demanding of the drying baskets. The rotating of all the baskets at a same or uniform rotational speed can be inefficient and slow the drying process. Accordingly, it would be advantageous to be able to rotate the different baskets at different rotational speeds depending upon the needs of the capsules being dried therein.
A capsule dryer, according to the principles of the present invention, utilizes an upper level having a plurality of drying baskets and a lower level having a plurality of drying baskets disposed beneath the upper level of drying baskets. By providing upper and lower levels of drying baskets, the footprint of the capsule dryer can be reduced while providing the same or superior drying capabilities. Accordingly, the required area in a factory using the capsule dryer can be reduced thus allowing additional space in the factory for other equipment or tasks.
In another aspect of the present invention, the rotation of the drying baskets at the different levels are independently controlled and driven. This advantageously enables the upper and lower level baskets to be driven at different rotational speeds according to the needs of the capsules being dried therein. Accordingly, more efficient operation of the capsule dryer can be achieved along with an increase in throughput capacity.
In yet another aspect of the present invention, the capsule dryer utilizes a drive mechanism to rotate the drying drums. There is a programmable control device which is operable to control operation of the drive mechanism. The use of a control device is advantageous in that it facilitates the controlling of the operation and can also be integrated into or utilize the same control device that controls the encapsulation machine that produces the soft capsules. The control device can also control the routing of the capsules from one drying basket to the next drying basket. The control device is advantageous in that it can facilitate the transferring of capsules from one basket to the next and coordinate the same with all the baskets. This coordination can increase the throughput of the capsule dryer, increase the efficiency of the drying operation and reduce the complexity of the control system.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.